Nobody wants to completely ban AI or training. You can have progress in this area and still respect people's intellectual property. Framing this as destroying progress is silly.
Why can't they train on the code they own, such as Windows sources for example?
Or even better, why can't they release CoPilot itself under an open source license that is compatible with the licenses of code they would like to train on?
Also, I don't think anyone cares about the monetary aspects. The idea behind the GPL style license is to make sure that code remains free, regardless of what or who uses it. Freedom in this context refers to the ability study the code, modify the code, and distribute any modifications. Without the GPL the code can be used in a proprietary product which strips those rights away from users of the product.
Copeleft uses copyright laws to attempt to guarantee freedom for users. This is the inverse of what normal copyright does, which is allow a single entity to sit on the ideas and not allow other's to benefit from them.
If we can just strip copyleft licenses from projects, we are giving up those guarantees that GPL code will remain free for all users.
The GPL is trying to do it's job here, not slow down progress. Progress would be everyone benefiting from the technology behind CoPilot, rather than just MicroSoft sitting on the project and selling it as a service.